Windows 10 download won’t start

my internet traffic is limited by ISP and it's free only during a specific period throughout the day (2:00am-7:00am). … how can I schedule "windows updates" for "windows 8.1 pro" to start/stop at specified times?

By default, Windows will check for updates at 3am which should suit your situation, so you should leave it set to automatically check for updates instead of doing it manually. It should be waking the system at 3am to do the check, but if it’s not doing so even when set to automatic updates, then it will do it the next time you boot up, which could be past 7am. To let Windows wake your system at night to check for updates:

1. Go to Action Center
2. Look for the Automatic Maintenance section
3. Put a check in the Allow scheduled maintenance to wake up my computer at the scheduled time check-box
4. Optionally set the exact time (to the hour) when Windows should wake up and check

at that time(2AM - 7AM), the PC is engaged in downloading videos & other files. So how can let it run schedule maintenance at that time as this can affect the downloading and other processes. I want to run only the "windows update" not any other maintenance work at that time.

You want to download Windows updates only during the free-bandwidth period between 2-7am, but you don’t want the download of Windows updates to interfere with P2P downloading during that same period? I’m not sure what your question is anymore, but if you are asking about preventing the system from being rebooting after an update, then you can do that. How will depend on what edition of Windows you are using.

• Windows Professional and up:

  1. Run gpedit.msc
  2. Navigate to Computer Configuration → Administrative templates → Windows Components → Windows Update
  3. Set No auto-restart with logged on users for scheduled automatic updates installations to Enalbed
     
     

• Windows Home and down:

  1. Run regedit
  2. Navigate to HKEY_LOCAL_MACHINE\Software\Policies\Microsoft\Windows\WindowsUpdate\AU
  3. Select Edit → New → DWORD
  4. Enter NoAutoRebootWithLoggedOnUsers for the value name
  5. Double-click it and enter 1 for the value

Figure 1: Windows update schedule is now part of the general maintenance schedule

Use hibernate, if you can. Hibernate should let you turn off your laptop and resume exactly where you left off. Sleep is a good option too.

Otherwise, the update will restart on the next update check, but part (or all) of the download may be lost. I would not worry about stopping it or other problems.